Relationship of the roller burnishing process parameters with the surface and subsurface properties of Inconel 718

This study aims to evaluate how deep the roller burnishing (RB) operating variables (temperature, number of passes, and load applied by the bearing) affect the surface properties of an Inconel 718 part, in particular the surface roughness and nanohardness, based on nanoindentation results and image analysis techniques by confocal microscopy. It was evaluated how the intensity of these same variables of roller burnishing operations caused the phenomenon of strain-softening. Through the results obtained, it can be noted that, with up to two passes of RB, the surface roughness improves significantly. By increasing the number of RB passes, a discrete phenomenon of strain-softening deformation between the third and fourth RB passes in both operations at room temperature and at 310℃ was verified. For all RB operations (at room temperature and 310℃), the nanohardness levels (HV) were higher than those of the only turned sample, showing that, regardless of the test temperature the nanohardness of the part that underwent the RB operation increased. Metallographic analysis of the samples that underwent RB was performed and the abundant presence of the δ phase was observed. A gap was filled in research involving both the roller burnishing technique and the resulted properties of the Inconel 718.